1. Field of the Invention
The present invention relates to wireless communication and more particularly, to a method and an apparatus for transmitting sounding reference signals in a wireless communication system.
2. Related Art
The 3rd Generation Partnership Project (GPP) Long Term Evolution (LTE)/LTE-A (Advanced) refers to wireless communication system specifications. In the LTE/LTE-A system, a Sounding Reference Signal (SRS) is transmitted to measure a uplink channel through which a user equipment transmits a signal to a base station.
In the uplink transmission, a control channel, Physical Uplink Control Channel (PUCCH), and a data channel, Physical Uplink Shared Channel (PUSCH) can be transmitted. The PUCCH is transmitted at the both edges of an allocated frequency band, and the PUSCH is transmitted from within the both frequency bands to which the PUCCH is transmitted.
Meanwhile, a carrier with a new structure not taking account of backward compatibility with existing cells (which is called a New Carrier Type (NCT)) is considered for use in future wireless communication systems. For example, in case an existing cell transmits a cell-specific reference signal (which is called a Cell-specific Reference Signal (CRS)) at each subframe during downlink transmission; and a synchronization signal, a broadcast channel, and a PDCCH are transmitted, the NCT used for the downlink can transmit the CRS at particular times rather than each subframe; and the structure of the synchronization signal, the broadcast channel, and the PDCCH can be configured differently.
In particular, a downlink NCT can be used mostly for data transmission, and in this case, the downlink NCT can reduce control channels such as the PDCCH. In the case of a uplink NCT corresponding to the aforementioned downlink NCT, transmission of a PUCCH may not be employed.
A conventional SRS has been designed to handle PUCCH transmission. In other words, the SRS has been defined to be transmitted in the frequency band of a uplink carrier, not including the frequency band in which the PUCCH is transmitted. Therefore, in case a conventional SRS transmission method is applied the same with respect to a carrier which does not deal with the PUCCH transmission such as the NCT or a uplink carrier corresponding to the NCT, SRS transmission may not be carried out in some frequency domain.